Which J.K. Rowling book became the screenplay source for the 2016 film Fantastic Beasts?

Fantastic Beasts and Where to Find Them became the screenplay source for the 2016 film Fantastic Beasts and Where to Find Them.

The original book was published in 2001 as a charity companion to the Harry Potter series. It is presented as a Hogwarts textbook by the fictional author Newt Scamander and describes magical creatures in a reference-book format.

Rowling later wrote the screenplay for the 2016 film, which expanded Newt Scamander into the central character of a new story set in the wizarding world. The film is not a direct adaptation of a conventional narrative novel; it uses the textbook’s fictional author and subject as foundations for an original screenplay.

The film began a planned series featuring Eddie Redmayne as Newt. This distinction explains why the film title matches the companion book while the plot is much more developed than the brief textbook entries.